The treatment of metastatic renal cell carcinoma remains unsatisfactory. Several therapeutic trials with retinoids and r interferon alpha (r IFN alpha) suggest a synergic antiproliferative effect between retinoid acid and r IFN alpha. Pharmacokinetic data and the mechanism of antiproliferative effects of retinoids are discussed. The induction of growth arrest is related to the expression of specific retinoid receptors. Further investigations are required in order to target the patient population which requires this therapy.